EGFR expression and HER2/neu overexpression/amplification in endometrial carcinosarcoma.

OBJECTIVE: Endometrial carcinosarcomas are aggressive biphasic neoplasms traditionally treated as a high-grade uterine sarcoma. Epidermal growth factor receptor (EGFR) and HER2/neu (HER2) tyrosine kinases have been implicated in the development and progression of several human cancers and are targets for therapeutic intervention. The aim of this study was to evaluate for HER2 and EGFR expression in cases of endometrial carcinosarcoma.

METHODS: Formalin-fixed, paraffin-embedded sections from 55 cases of confirmed endometrial carcinosarcoma were immunostained with commercially available antibodies to EGFR and HER2. Fluorescent in situ hybridization for HER2 gene amplification was performed on all cases showing 2+ or 3+ HER2 staining by immunohistochemistry. HER2 gene amplification and EGFR expression were correlated with several prognostic variables.

RESULTS: EGFR expression was identified in the majority of tumors (45/55, 82%). HER2 overexpression (3+) was seen in 14/55 (25%) cases and HER2 gene amplification was seen in 11 (20%) cases. EGFR expression and HER2 gene amplification did not show significant correlation with disease progression, disease-free survival or overall survival. The carcinomatous component of tumors more frequently showed HER2 overexpression as compared to the sarcomatous component (25% vs. 4%, P = 0.008). The sarcomatous component of tumors more frequently showed EGFR overexpression as compared to the carcinomatous component (44% vs. 24%, P = 0.04).

CONCLUSIONS: EGFR and HER2 appear to play a role in the carcinogenesis of endometrial carcinosarcomas. The carcinomatous and sarcomatous elements of these tumors showed consistent differences in HER2 and EGFR expression patterns supporting biologic differences between these components. Studies evaluating the clinical utility of HER2 or EGFR targeted therapy in these tumors appear warranted.